IBM TM1 / Planning Analytics - MDX Reference Guide

This post will hopefully get more developers using MDX within their sets and views.
The intention is to expose MDX commands that work in TM1, their syntax or usage and some examples or applications.

This is a guide and not gospel – I am sure there are many ways of doing the same thing as well as better ways.
You will see that some examples switch around certain functions – this may be by design or accidental.

There are also gaps as this project is a work in progress. Similarly, alignment of syntax needs to be reviewed and edited.

Most importantly was getting something out here to begin with. Just like with any TM1 model, something is better than nothing.
Expect errors and omissions but please feedback so that I can update/correct for everyone’s benefit.

I am not going to try and replicate any websites or MDX books of which there are many.
My go-to reference is Multidimensional Expressions (MDX) Reference – SQL Server 2012 Books Online, Microsoft

My examples are based on a simple model with an Expense cube built with a Period, Cost Centre and other dimensions. Some examples may reference the cubes in the SData sample where I could not find a suitable example in the Period dimension.
My Period dimension is deliberately designed with leaf elements as YYYY-MMM e.g. 2021-JAN – these do not sort chronologically and is perfect for some examples.
Also, I have assumed a July start or Period 1.
My Period dimension has multiple rollups grouping Periods into Fiscal Years as well as Periods into Quarters, Halves and Fiscal Years.
These have also been configured in the }HierarchyProperties cube to drive some of the Level queries.

You can create your own Period dimension per below to play with the examples.

The Cost Centre dimension referenced is simple containing a Total with children. The leaf elements have two attributes that are used in the examples: Primary Cost Centre and Division. You can configure your own dimension accordingly to test some of the examples.


I also created a basic Client Assumption cube to read the Current Period for the user in some examples. You could create this per the below cube view.

That should suffice for most of the model needed to test the examples. You can create other objects as required based on the examples.

TM1 / Planning Analytics – MDX Reference Guide

ARITHMETIC OPERATORSDescription/NotesSyntaxExample
+ Add, Positive  
/ Divide  
* Multiply  
– Subtract, Negative  
^ (Power)  
   
BITWISE OPERATORS
ANDPerforms a logical conjunction on two numeric expressions.<Expression 1> AND <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) <> “” AND
[Cost Centre].CurrentMember.Properties(“Division”) <> “”
) }

Should give you Cost Centres where there is both a value in the Primary Cost Centre and Division attributes.
NOTPerforms a logical negation on a numeric expression.NOT <Expression 1>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
NOT [Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) <> “” AND
[Cost Centre].CurrentMember.Properties(“Division”) <> “”
) }

Should give you Cost Centres where the Primary Cost Centre attribute is blank and Division attributes is not blank.
ORPerforms a logical disjunction on two numeric expressions.<Expression 1> OR <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) = “” OR
[Cost Centre].CurrentMember.Properties(“Division”) = “”
) }

Should give you Cost Centres where Primary Cost Centre, Division attributes or both are blank.
XORPerforms a logical exclusion on two numeric expressions. Returns True when only one expression evaluates to True. Either Expression 1 or Expression 2 is True, not both.<Expression 1> XOR <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) = “” XOR
[Cost Centre].CurrentMember.Properties(“Division”) = “”
) }

Should give you Cost Centres where either the Primary Cost Centre or the Division attributes are blank, but not both.
ISPerforms a logical comparison on two object expressions.
Use square brackets if your level contains a space e.g. [Fiscal Year]
Best to fully qualify using dimension and value e.g. [Period].[Quarters] where the name may appear in other dimensions causing ambiguity.
<Expression 1> IS (<Expression 2> | NULL )FILTER({TM1SUBSETALL( [Period] )},
[Period].CurrentMember.Level IS [Period].[Quarters])

Gives you Periods linked to the same level as which Quarters was defined.
   
COMPARISON OPERATORS
=Is Equal To – Applies to numeric and string comparisons<Expression 1> = <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) = “”
) }

Returns a set of Cost Centres where the Primary Cost Centre attributes is blank.
<>Is Not Equal to – Applies to numeric and string comparisons<Expression 1> <> <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Cost Centre].CurrentMember.Properties(“Primary Cost Centre”) <> “”
) }

Returns a set of Cost Centres where the Primary Cost Centre attributes is not blank.
>Is Greater Than<Expression 1> > <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Expense].(…,[Amount]) > 50000
) }

Returns a set of Cost Centres where specified value in the Expense cube is greater than 50,000
>=Is Greater Than or Equal To<Expression 1> >= <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Expense].(…,[Amount]) >= 50000
) }

Returns a set of Cost Centres where specified value in the Expense cube is greater than or equal to 50,000
<Is Less Than<Expression 1> < <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Expense].(…,[Amount]) < 0
) }

Returns a set of Cost Centres where specified value in the Expense cube is negative.
<=Is Less Than or Equal To<Expression 1> <= <Expression 2>{ FILTER(
{TM1SUBSETALL( [Cost Centre] )},
[Expense].(…,[Amount]) <= 0
) }

Returns a set of Cost Centres where specified value in the Expense cube is zero or negative.
TRUENot an operator but a literal used in comparisons/filters  
FALSENot an operator but a literal used in comparisons/filters  
   
CONCATENATION OPERATORS
+Combine or join multiple strings<String 1> + <String 2>{StrToMember(“[Period].[Period].[” +
[Client Assumption].( StrToMember(“[}Clients].[” + UserName + “]”),
[Client Assumption Measures].[Current Period]) + “]”)}

Concatenates the value from an assumptions cube with the hierarchy to create a valid member.
   
SET OPERATORS
– (Except)Returns the difference between two sets, removing duplicate members. This operator is functionally equivalent to the Except function.<Set 1> – <Set 2>Did not work in a Dimension set but may work with a SELECT statement
* (Crossjoin)Returns the cross product of two sets. This operator is functionally equivalent to the Crossjoin function.
Used in an MDX view where you have dimensions stacked e.g. Product within Customer.
<Set 1> * <Set 2>SELECT {TM1SubsetToSet([Expense Measures].[Expense Measures],”Default”,”public”)} ON 0, {TM1SubsetToSet([Cost Centre].[Cost Centre],”Default”,”public”)} * {TM1SubsetToSet([Reporting Currency].[Reporting Currency],”Default”,”public”)} ON 1 FROM [Expense] WHERE …
: (Range)Returns a naturally ordered set, with the two specified members as endpoints and all members between the two specified members included as members of the set.<Member 1> : <Member 2>[Period].[Period].[2021-JAN] : [Period].[Period].[2021-DEC]

Should return periods from Jan to Dec
+ (Union)Returns a union of two sets, excluding duplicate members.<Set 1> + <Set 2>{[Period].[Period].[2020-JAN] : [Period].[Period].[2020-DEC]} +
{[Period].[Period].[2022-JAN] : [Period].[Period].[2022-DEC]}

Will return a set with the range of members from the first expression and second expression. Any overlaps do not result in duplicates.
   
STRING FUNCTIONS
NameReturns a string containing the member name<Member expression>.NameFILTER({TM1SUBSETALL( [Period] )},
RIGHT([Period].CurrentMember.Name,1)=”V”)

Returns elements where the Name of the member ends in a V e.g. 2021-NOV
UniquenameReturns a string containing the member unique name.
Values are enclosed in square brackets.
<Member expression>.UniqueNameFILTER({TM1SUBSETALL( [Period] )},
INSTR(1, [Period].CurrentMember.UniqueName, “^”, 0) = 0)

Returns members that are unique in the hierarchy i.e. do not form part of any other rollups and thus are not further qualified with a caret (^)
PropertiesReturns a string, or a strongly-typed value, that contains a member property value i.e. Attribute value.Member_Expression.Properties(Property_Name [, TYPED]){ORDER(
{TM1FILTERBYLEVEL( {TM1SUBSETALL( [Period] )}, 0)},
[Period].CurrentMember.Properties(“Month”),
BASC)}

Returns a set of leaf level months orders by Month which is numeric.
2021-JAN, 2021-FEB etc. do not sort chronologically naturally.
GenerateExecutes a string function on each member of the set, almost like a For Each Member statement.Generate(<Set 1>, <Set 2> [, ALL]){GENERATE(
{[Period].[2023-MAR]},
{[Period].CurrentMember,
StrToMember(“[Period].[” + [Period].CurrentMember.Name + ” YTD]”),
[Period].CurrentMember.Parent,
[Period].CurrentMember.LAG(12)}
)}

Should return 2023-MAR itself, being the CurrentMember then 2023.09 YTD, 2023.FY and 2022-APR
UserNameReturns the domain name and user name of the current connection.UserName{StrToMember(“[Period].[Period].[” +
[Client Assumption].( StrToMember(“[}Clients].[” + UserName + “]”),
[Client Assumption Measures].[Current Period]) + “]”)}

UserName is the string value the active client and used to lookup the current period in the assumption cube. In this case, my value in the cube is 2021-JAN and this is returned as a member.
InstrReturns the position of the first occurrence of one string within another.
NB: 4th parameter, compare in TM1 is used as 0 for case-sensitive, 1 for ignore case.
InStr([start, ]searched_string, search_string[, compare]){FILTER(
{[Period].[Period].Members},
InStr(1, [Period].[Period].CurrentMember.Name, “ju”,1)>0
)}

Returns periods containing JU, Ju, jU or ju – remember parameter 4 to manage case.
UCaseConvert a string to upper caseUCase(<string>){FILTER(
{[Period].[Period].Members},
InStr(1, UCase([Period].[Period].CurrentMember.Name), “JU”,0)>0
)}

Returns periods containing JU e.g. 2021-JUL
LCaseConvert a string to lower caseLCase(<string>){FILTER(
{[Period].[Period].Members},
InStr(1, LCase([Period].[Period].CurrentMember.Name), “ju”,0)>0
)}

Returns periods containing JU e.g. 2021-JUL
LeftReturn n number of characters from the start of a stringLeft(<string>,<count>){FILTER(
{[Period].[Period].Members},
LEFT([Period].[Period].CurrentMember.Name, 4)=”2022″
)}

Returns periods where the first 4 characters are 2022 – could be N or C or S elements.
RightReturn n number of characters from the end of a stringRight(<string>,<count>){FILTER(
{[Period].[Period].Members},
RIGHT([Period].[Period].CurrentMember.Name, 3)=”JUL”
)}

Returns periods where the last 3 characters are JUL – could be N or C or S elements. Does not appear case sensitive as it would include as a match 2021-Jul, 2021-jul too.
   
CASTING FUNCTIONS
MemberToStrReturn a string containing the uniquename of the memberMemberToStr(<Member>){FILTER(
{[Period].[Period].Members},
MemberToStr([Period].[Period].CurrentMember)=”[Period].[2022.FY^2022-JAN]”
)}
StrToMemberReturns the member as specified in the string expressionStrToMember(<string expression> [, CONSTRAINED])STRTOMEMBER(“[Period].[Period].[” +
SETTOSTR(
TM1SubsetToSet([Period].[Period] , “_S-Current Year” , “public”)) + “]”
)
StrToValueReturn the value of a specified string. NB: Will fail on Nulls and my require the use of IIF() to trapStrToValue(<string expression>){FILTER(
{[Period].[Period].Members},
StrToValue([Period].[Period].CurrentMember.Properties(“LEVEL_NUMBER”))=0
)}
SetToStrReturns a string based on the set expression. Will bring back values with braces and a comma e.g. {2022-JAN}, you may need to trim these.SetToStr(<Set> )STRTOMEMBER(“[Period].[Period].[” +
SETTOSTR(
TM1SubsetToSet([Period].[Period] , “_S-Current Fiscal Year” , “public”)) + “]”
).NEXTMEMBER
StrToSetReturn a set as specified by the string in the set specification. MS MDX has CONSTRAINED as an optional 2nd parameter which is not supported in TM1StrToSet(<set specification> [, CONSTRAINED])StrToSet( “[Period].[Period].Members” )
StrToTupleReturns a tuple as specified in the string expressionStrToTuple(<string expression> [, CONSTRAINED])Need an example using SELECT
TupleToStrReturns a string containing tuples. Could be used to parse in other functionsStrToTuple(<tuple expression>)Need an example using SELECT
NameToSetReturns a set based on a member nameNameToSet(<member name>){NameToSet( “[Period].[Period].[2022.FY^2022-JAN]”)}
   
LOGICAL FUNCTIONS
ISPerforms a logical comparison on two object expressions to see if they are exactly the same.<Expression1> IS <Expression2>No useful example of how to use:
FILTER(
{TM1SUBSETALL( [Period] )},
[Period].CurrentMember IS [Period].[2020-JUL]))
IIFReturns one of two values determined by a logical test.IIf(Logical_Expression, Expression1, Expression2)FILTER(
{TM1SUBSETALL( [Period] )},
StrToValue(
IIF([Period].CurrentMember.Properties(“Period Index”)=””,
“0”,
[Period].CurrentMember.Properties(“Period Index”)))>0)
Case, When, Else, EndLets you conditionally return specific values from multiple comparisons.CASE <expression>
WHEN <case 1> then <expression 1>
WHEN..
ELSE
<expression>
END
{ STRTOMEMBER(“[Period].[” +
CASE LEFT( RIGHT( SetToStr( {[Period].[Period].[_S-Current Period].Item(0)} ), 10), 8)
WHEN “2022-JAN” then “2021.Q1”
WHEN “2021-APR” then “2021.Q2”
ELSE
SetToStr( {[Period].[Period].[_S-Current Period].Item(0)} )
END
+”]”) }
IsLeafTest is a member is a Leaf elementIsLeaf(<Member>)FILTER(
{TM1SUBSETALL( [Period] )},
IsLeaf([Period].CurrentMember))
IsAncestorTest if a specified member is an Ancestor of another specified member.IsAncestor(<Member1>,<Member2>)FILTER(
{TM1SUBSETALL( [Period] )},
IsAncestor([Period].CurrentMember,[Period].[2022.Q3]))
Returns all Ancestors of 2022.Q3
IsEmptyTest if a cell, property or value is emptyIsEmpty(<Expression>)FILTER(
{TM1SUBSETALL( [Period] )},
IsEmpty([Sales].([…]))
IsSiblingTest if a member is a sibling of another specified member.IsSibling(<Member>,<Sibling Member>)FILTER(
{TM1SUBSETALL( [Period] )},
IsSibling([Period].CurrentMember,[Period].[2022.Q3]))
IsGenerationTest if the specified Member is in the specified Generation (Level)IsGeneration(<Member>,<Generation>)FILTER(
{TM1SUBSETALL( [Period] )},
IsGeneration([Period].CurrentMember,2))
IsNullNot supported yetISNULL(MDX_expression,value_if_null)Would be useful to set blanks to “0” etc. avoids IIF()
*Boolean values returned   
   

MEMBER FUNCTIONS AND EXPRESSIONS

AllMembersReturns a set that contains all members of the specified hierarchy or level.
Will include all calculated members in that hierarchy or level.
<hierarchy expression>.AllMembers
<level expression>.AllMembers
[Period].AllMembers or
[Period].[level000].AllMembers or
[Period].[Halves].AllMembers
MembersReturns the set of members in a dimension, level, or hierarchy. Returns Members, not Elements i.e. will repeat where element is in multiple rollups<dimension expression>.Members
<hierarchy expression>.Members
<level expression>.Members
[Period].Members
DefaultMemberReturn the default member for the dimension/hierarchy as specified in the }HierarchyProperties cube.<dimension expression>.DefaultMember{[Period].DefaultMember}
CurrentReturns the current tuple from a set during iteration.<Set>.CurrentNeed a useful example
CurrentMemberReturns the current member along a specified hierarchy during iteration.Hierarchy_Expression.CurrentMemberFILTER(
{TM1SUBSETALL( [Period] )},
IsLeaf([Period].CurrentMember))
NextMemberReturns the next member in the level that contains a specified member.Member_Expression.NextMember{[Period].[2020-JUN].NextMember}
gives you 2020-JUL
PrevMemberReturns the previous member in the level that contains a specified member.Member_Expression.PrevMember{[Period].[2020-JUN].PrevMember}
gives you 2020-MAY
ParentReturns the parent of a member.Member_Expression.ParentReturns the first parent of the member
{TM1Member([Period].[Current Month].Item(0),0).Parent}
Root  
LevelReturns the Level of a memberMember_Expression.Level[Period].[2021-Q3].Level
LevelsReturns members from a specified Level using the Level Name or numberHierarchy_Expression.Levels( Level_Number )
or Hierarchy_Expression.Levels( Level_Name )
[Period].[Period].LEVELS(“Quarters”).MEMBERS
or [Period].[Period].LEVELS(1).MEMBERS
This  
AncestorA function that returns the ancestor of a specified member at a specified level or at a specified distance from the member.Ancestor(Member_Expression, Level_Expression)
or Ancestor(Member_Expression, Distance)
Returns an Ancestor from n levels higher. This returns Total Years which is the parent of 2021
{Ancestor(TM1Member([Period].[Current Month].Item(0),0),2)} or
Returns the Half that the period is in:
{Ancestor([Period].[2021-Q3^2021/07],[Period].[Halves])}
AncestorsReturns a set of ALL ancestorsAncestors(Member_Expression, Level_Expression)
Ancestors(Member_Expression, Distance)
Returns Ascendants without the current member
{TM1Member([Period].[Current Month].Item(0),0).Ancestors}
AscendantsReturns all of the ancestors of a member from the member itself up to the top of the member’s hierarchyAscendants(Member_Expression)Returns the Current Month and parent then its parent
{Ascendants(TM1Member([Period].[Current Month].Item(0),0))}
FirstSiblingReturns the first child of the parent of a member.Member_Expression.FirstSiblingReturns the first child in the rollup that the member is in i.e. 2021/01 in this case
{TM1Member([Period].[Current Month].Item(0),0).FirstSibling}
LastSiblingReturns the last child of the parent of a specified member.Member_Expression.LastSiblingReturns the first child in the rollup that the member is in i.e. 2021/12 in this case
{TM1Member([Period].[Current Month].Item(0),0).LastSibling}
FirstChildReturns the first child of a specified member.Member_Expression.FirstChildReturns 2021/01 given 2021
{[Period].[2021].FirstChild}
LastChildReturns the last child of a specified member.Member_Expression.LastChildReturns 2021/12 given 2021
{[Period].[2021].FirstChild}
CousinReturns the child member with the same relative position under a parent member as the specified child member.Cousin( Member_Expression , Ancestor_Member_Expression )Returns the same month in the specified year i.e. 2023/06:
{Cousin([Period].[Period].[2021/06], [Period].[Period].[2023])}
OpeningPeriodReturns the first sibling among the descendants of a specified level, optionally at a specified member.OpeningPeriod( [ Level_Expression [ , Member_Expression ] ] ){OpeningPeriod([Period].[Period].[Quarters],[Period].[Period].[2022-H2])}
Returns 2022-Q3 as this is the first Quarter in 2022-H2
ClosingPeriodReturns the member that is the last sibling among the descendants of a specified member at a specified level.ClosingPeriod( [ Level_Expression [ ,Member_Expression ] ] ){ClosingPeriod([Period].[Period].[Quarters],[Period].[Period].[2022-H2])}
Returns 2022-Q4 being the last Quarter in 2022-H2.
ParallelPeriodReturns a member from a prior period in the same relative position as a specified member.ParallelPeriod( [ Level_Expression [ ,Index [ , Member_Expression ] ] ] ){ParallelPeriod([Period].[Period].[Quarters],4,[Period].[Period].[2022-Q4])}
Returns 2021-Q4 which is 4 quarters prior
HeadReturns the first specified number of elements in a set, while retaining duplicates.Head(<Set> [ ,Count ] ){HEAD([Period].[2020.FY].Children,6)}
TailReturns a subset from the end of a set.Tail(<Set> [ ,Count ] ){TAIL([Period].[2020.FY].Children,6)}
LeadReturns the member that is a specified number of positions following a specified member along the member’s level.Member_Expression.Lead( Index ){[Period].[2020-JUL].LEAD(6)}
Gives you 2021-JAN
LagReturns the member that is a specified number of positions before a specified member at the member’s level.Member_Expression.Lag(Index){[Period].[2020-JUL].LAG(6)}
Gives you 2020-JAN
ValueDefault property of a member  
   
TUPLE FUNCTIONS
CurrentReturns the current tuple from a set during iteration.  
ItemThe Item function returns a member from the specified tuple.TM1Member([Period].[Current Year].ITEM(1),0 )
   

SET FUNCTIONS AND EXPRESSIONS

AddCalculatedMembersReturns a set generated by adding calculated members to that specified set. Example needed
ChildrenReturns the set of children of a specified member.Member_Expression.ChildrenReturns the months in the quarter in this case:
[Period].[2021-Q3].Children
SiblingsReturns the siblings of a specified member, including the member itself.Member_Expression.SiblingsReturn all periods in the year based on current month.
{TM1Member([Period].[Current Month].Item(0),0).Siblings}
DescendantsReview parameters e.g. SELF, ABOVE, LEAVES etc.Descendants(Member_Expression [ , Level_Expression [ ,Desc_Flag ] ] )Descendants(TM1SubsetToSet([Period].[Period], “FiscalPeriods” , “public” ),4,Leaves)
MembersRetrieves a set containing all of the members from a dimension, hierarchy, or level.Dimension_Expression.Members
Hierarchy_Expression.Members
Level_Expression.Members
{[Period].Members}
{[Period].[Halves].Members}
In the first MDX, all members in the Period dimension are returned. In the second, members in the Halves level are returned.
DistinctEvaluates a specified set, removes duplicate tuples from the set, and returns the resulting set.Distinct(<Set>)DISTINCT({[Period].[2020.FY].Children,[Period].[2020.Q3].Children})
The set would have repeated 2020-JAN, 2020-FEB and 2020-MAR but removed using Distinct
HierarchizeOrganize members into the Hierarchical order.Hierarchize(<Set> [ , POST ] ){Hierarchize([Period].[Halves].Members + [Period].[Fiscal Years].Members,POST)}
UnionReturns a set that is generated by the union of two sets, optionally retaining duplicate members.Union(<Set 1>, <Set 2>[, ALL]){UNION( [Period].[2020.FY].Children,[Period].[2021.FY].Children )}
Combines set 1 and set 2
{UNION( [Period].[2020.FY].Children, {[Period].[2020-JAN]}, ALL )}
Will combine the sets and in this case have a duplicate entry for 2020-JAN
IntersectReturns members appearing in both sets. Duplicates can optionally be retained using the ALL parameterIntersect(<Set>1 , Set_Expression2 [ , ALL ] )INTERSECT(
TM1SUBSETALL( [Period] ),
TM1SubsetToSet( [Period], “_S-Quarter”, “Public” ),
ALL
)
ExceptEvaluates two sets and removes those tuples in the first set that also exist in the second set, optionally retaining duplicates. {Except( {[Period].[2020.FY].Children},
{[Period].[2019-NOV],[Period].[2019-DEC]} )}
Will return all months then exclude Nov and Dec
ExtractThis is the opposite of the CrossJoin function and returns a set of tuples from the extracted hierarchy elements.Extract(<Set>, Hierarchy_Expression1 [,Hierarchy_Expression2, …n] )Need an example using a Select statement
FilterExclude members based on criteria FILTER(
{TM1SUBSETALL( [Scenario] )},
VAL([Scenario].CurrentMember.Properties(“Flag”))=1)
OrderOrder contents of a set ASC, DESC, BASC, BDESC
Note that ASC and DESC sorts within the member’s parent.
BASC and BDESC breaks the hierarchies and sort the elements like a flat list.
 {ORDER(
{TM1FILTERBYLEVEL( {TM1SUBSETALL( [Period] )}, 0)},
[Period].CurrentMember.Properties(“Month”),
BASC)}

Returns a set of leaf level months orders by Month which is numeric.
2021-JAN, 2021-FEB etc. do not sort chronologically naturally.
SubsetSkip N number of members and returns the remainder like the MID function for characters. Position is zero-based.Subset(<Set>, Start [ ,Count ] )SUBSET(
{TM1SubsetToSet([Period],”_S-All N”,”public”)},5,4)
In this example element 5 is 2019-May, so 2019-May and the next 3 elements are returned.
LastPeriodsReturns a set of members up to and including a specified member.LastPeriods(Index [ ,Member_Expression ] )LastPeriods(4,[Period].[Period].[2022/08])
Returns 2022/08 and the prior 3 periods – 4 members in all
PeriodsToDateReturns a set of sibling members from the same level as a given member, starting with the first sibling and ending with the given member, as constrained by a specified level in the Time dimension.PeriodsToDate( [ Level_Expression [ ,Member_Expression ] ] )PeriodsToDate([Period].[Period].[Years],[Period].[Period].[2022-Q3^2022/08])
Returns 2022/01 and all periods to 2022/08
BottomCountSorts a set in ascending order, and returns the specified number of tuples in the specified set with the lowest values.BottomCount(<Set>, Count [,Numeric_Expression])BOTTOMCOUNT(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
10.0 ,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Sorts and returns bottom 10 models based on units sold – lowest sales (SData)
BottomPercentSorts a set in ascending order, and returns a set of tuples with the lowest values whose cumulative total is equal to or greater than a specified percentage.BottomPercent(<Set>, Percentage, Numeric_Expression)BOTTOMPERCENT(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
10 ,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Returns models where the aggregate value is within 10% of the total for all models
BottomSumSorts a set and returns the bottom most elements whose cumulative total is at most a specified value.BottomSum(<Set>, Value, Numeric_Expression)BOTTOMSUM(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
1000 ,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Returns all members where the sum of units is 1000 or less
TopCountSorts a set in descending order and returns the specified number of elements with the highest values.TopCount(<Set>,Count [ ,Numeric_Expression ] )TOPCOUNT(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
10.0 ,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Sorts and returns top 10 models based on units sold (SData)
TopPercentSorts a set in descending order, and returns a set of tuples with the highest values whose cumulative total is equal to or greater than a specified percentage.TopPercent(<Set>, Percentage, Numeric_Expression)TOPPERCENT(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
10 ,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Returns models where the aggregate value contributes 10% of the total for all models
TopSumSorts a set and returns the topmost elements whose cumulative total is at least a specified value.TopSum(<Set>, Value, Numeric_Expression)TOPSUM(
TM1SubsetToSet([model].[model] , “_S-All N” , “public”) ,
40000000,
[SalesCube].([actvsbud].[Actual], [region].[Argentina], [account1].[Units], [Month].[1 Quarter]))
Returns members where the sum is at least 40,000,000 – 3 members returned as the first 2 members was below 40 mil and needed a 3rd member to take it over the threshold.
DrilldownLevelDrills down the members of a set to one level below the lowest level represented in the set, or to one level below an optionally specified level of a member represented in the set.DrilldownLevel(<Set> [ , , Index ] )
DrilldownLevel(<Set> [ , Level_Expression ] )
DrilldownLevel(
{[Period].[Quarters].Members})
Expands each member of quarters, only to 1 level, not recursive.
Similarly DrilldownLevel({[Period].[2020.FY]}) expands the year showing the year and month.

DrilldownLevel({[Period].[2020.FY HQ]},,0) will drill into the first hierarchy of the expression.
DrilldownLevelTopDrills down the topmost members of a set, at a specified level, to one level below.DrilldownLevelTop(<Set>, <count> [,[<level_expression>] [,[<numeric_expression>][,INCLUDE_CALC_MEMBERS]]])DrilldownLevelTop( {[Period].[2020.FY HQ]}, 1, [FISCAL YEAR])
Will return 2020.FY HQ and the first half as we specified a count of 1. If we changed this to 2, would get the year and both Halves
DrilldownLevelBottomDrills down the bottommost members of a set, at a specified level, to one level below.DrilldownLevelBottom(<Set>, Count [ , Level_Expression [ ,Numeric_Expression ] ] )Example needed – seems to behave like DrilldownLevelTop
DrilldownMemberDrills down the members in a specified set that are present in a second specified set.DrillDownMember(<Set 1>, <Set 2> [,[<target_hierarchy>]] [,[RECURSIVE][,INCLUDE_CALC_MEMBERS]])DrillDownMember({[Period].[Fiscal Periods].Children},{[Period].[2020.FY]})
Will return all Fiscal years and all periods for 2020.FY
DrilldownMemberTopDrills down the members in a Set 1 that are present in Set 2. You can limit the result set to a specified number of members using the count parameter.DrillDownMemberTop(<Set 1>, <Set 2>, <Count> [,[<Numeric_Expression>] [,[<Hierarchy>]] [,[RECURSIVE][,INCLUDE_CALC_MEMBERS]]])DrillDownMemberTop({[Period].[Fiscal Periods].Children},{[Period].[2020.FY]},5)
Will return all Fiscal years and first 5 periods for 2020.FY
DrillupLevelDrill members that are below a certain level upDrillupLevel(<Set>[, [level expression])DrillUpLevel( {TM1SubsetAll([Period])}, [Halves])
Will return the top levels rolling down until Halves. All levels below Halves are removed i.e. Quarters and Leaves
DrillupMemberReturns members from Set 1 that are not descendants of members in Set 2DrillupMember(<Set 1>, <Set 2>)DrillUpMember(
{Descendants([Period].[Fiscal Periods])},
{[Period].[2020.FY]})
Set 1 would have the Fiscal Periods total, each Fiscal Year and its Periods.
Set 2 has the one Fiscal Year. The result is that for all Fiscal Years, all months are shown, except for those in 2020.FY, only the 2020.FY parent is shown as descendants are drilled up to this member.
DrilldownMemberBottomReturns a specified number of members from Set 1 that exist in Set 2. Function can also be used to drill down on a hierarchy.
Not sure if <hierarchy> is supported – not tested.
DrillDownMemberBottom(<Set 1>, <Set 2>, <count> [,[<numeric_expresion>] [,[<hierarchy>]] [,[RECURSIVE][,INCLUDE_CALC_MEMBERS]]])DrilldownMemberBottom(
{[Period].[Fiscal Periods].Children},
{[Period].[2020.FY]},5)
Returns the Fiscal Years 2020.FY, 2021.FY etc. but drills down 2020.FY showing the first 5 children.
ToggleDrillStatePer TM1ToggleDrillState  
   

DIMENSION, HIERARCHY and LEVEL FUNCTIONS

Dimension.NameIntrinsic DIMENSION_NAME  
Hierarchy.NameIntrinsic HIERARCHY_NAME  
Level.NameIntrinsic LEVEL_NAME  
* Used in conjunction with other functions to obtain information about the members of a dimension, hierarchy, or level. 
   
COMMENTING
//Inline comments or own line  
Inline comments or own line  
/*…*/Blocked comments  
   
   
NUMERIC FUNCTIONS
LENReturns the length of a string FILTER({TM1SUBSETALL( [Period] )}, LEN([Period].CurrentMember.Name)=4)
VALReturns the value of a string (Nulls evaluate to 0) FILTER(
{TM1SUBSETALL( [Scenario] )},
VAL([Scenario].CurrentMember.Properties(“Flag”))=1)
CoalesceEmptyConverts an Empty but not Null value to a specified value

CoalesceEmpty( <Numeric_Expression> [ ,<Replacement_Numeric_Expression>,…n] )

 
Aggregate Need examples using SELECT
Avg Need examples using SELECT
Count  FILTER({TM1FILTERBYLEVEL({TM1SUBSETALL( [Period] )},0)},
COUNT({
Intersect({[Period].Members},{[Period].CurrentMember},ALL)
})>5)
Returns all members that appear in the hierarchy more than 5 times. This is due to multiple rollups like Quarters, YTD etc.
Could be used to find members with multiple parents where they should only have one.
Correlation  
Covariance  
CovarianceN  
DistinctCount  
LinRegIntercept  
LinRegPoint  
LinRegR2  
LinRegSlope  
LinRegVariance  
LookupCube  
Max  
Min  
Median  
Rank  
StdDevSame as StDev – Alias  
StDev  
StdDevPSame as StDevP – Alias  
StDevP  
Sum  
Var  
VarianceSame as Var – Alias  
VarP  
VariancePSame as VarP – Alias  
   
TM1 Specific MDX Functions

https://www.ibm.com/docs/en/planning-analytics/2.0.0?topic=mfs-tm1-specific-mdx-functions-1

TM1MemberReturns a member from a specified tuple/subset. Avoid using as PAW translates any subset with TM1Member to underlying code.TM1MemberTM1Member([Period].[_S-Current Recharge Quarter].ITEM(1),0 ),
TM1FilterbyPatternReturns members matching a specified pattern. An asterisk is used for any characters before or after, a question mark to indicate a particular position only.

TM1FILTERBYPATTERN( <set>, <pattern_str> )

Undocumented is the 3rd parameter for an attribute:

TM1FILTERBYPATTERN( <set>, <pattern_str>[, <attribute>] )

{TM1FILTERBYPATTERN( {TM1SUBSETALL( [Period] )}, “*JUN*”)}
Returns all members containing JUN e.g. 2020-JUN, 2021-JUN

{TM1FILTERBYPATTERN( {TM1SUBSETALL( [Period] )}, “202?-JUN”)}
Returns all Jun members in the 2020’s, excludes 2019-JUN
TM1FilterByLevelReturns members matching a level number (0=Leaf)TM1FILTERBYLEVEL( <set>, <level_number>){TM1FILTERBYLEVEL( {TM1SUBSETALL( [Period] )}, 0)}
Returns all Leaf elements i.e. those at the lowest level. May include String and Numeric, not only Numeric.
TM1DrillDownMemberDrills down a member like the expand button in TM1 but for each Member in Set 2. Seems to behave exactly like DrillDownMember above.TM1DRILLDOWNMEMBER( <set1>, <set2>|ALL [,RECURSIVE] )TM1DrillDownMember({[Period].[Fiscal Periods].Children},{[Period].[2020.FY]})
Will return all Fiscal years and all periods for 2020.FY
TM1SortSorts a set alphabetically, ignores hierarchiesTM1SORT( <set>, ASC|DESC )TM1SORT( {TM1SUBSETALL( [Period] )}, ASC)}
Will sort all elements alphabetically returning a mix of N and C levels
TM1SortByIndexSorts a set by index/ordinalTM1SORTBYINDEX( <set>, ASC|DESC )TM1SORTINDEX( {TM1SUBSETALL( [Period] )}, ASC)}
Will sort all elements based on their ordinal position or Index in the hierarchy
TM1SubsetAllReturns all Elements in a dimension, distinct, not all members.
Where an element appears in multiple rollups, only the first occurrence is returned, like using DISTINCT()
TM1SUBSETALL([<dimname>]){TM1SUBSETALL( [Period] )}
Will return all elements from Period without duplicates.
TM1SubsetToSetInserts the elements of a set into the current setTM1SubsetToSet(<Dimension>,<Hierarchy>,<SubsetName>[,<Public|Private])TM1SubsetToSet([Period], “_S-All N”, “public”)
Returns all the members from the underlying public subset.
TM1TupleSizeA count of members in the set/tupleTM1TupleSize 
TM1SubsetBasisA placeholder generated by the MDX recorded in Architect/Perspectives. Replace with a valid tuple. Not giving an example – if you see it, fix your code.
TM1RollUpRollup members from Set 1 to their parents if specified in Set 2TM1Rollup(<Set 1>, <Set 2>)TM1ROLLUP({[Period].[2020.FY].Children},{[Period].[2020-FEB],[Period].[2020-MAR]})
Will return all months and then roll up to the parents of 2020-FEB and 2020-MAR
TM1ToggleDrillStatePer MS MDX – Toggles the drill state of members between drilldown and drillllup modes.
Need a better example on this.
TM1TOGGLEDRILLSTATE(<Set 1>,<Set 2>,EXPAND_ABOVE|EXPAND_BELOW,RECURSIVE)
)
TM1TOGGLEDRILLSTATE(
{[Period].[FISCAL PERIODS].Children},
{DESCENDANTS([Period].[2021.FY])},
EXPAND_BELOW,
RECURSIVE
)
TM1ToggleExpandModeUsed to Expand Above or Below{TM1ToggleExpandMode(<set>,EXPAND_ABOVE|EXPAND_BELOW)}{TM1ToggleExpandMode({Descendants([Period].[2021.FY])},EXPAND_ABOVE)}
   

MDX VIEW RELATED KEYWORDS

WithWITH MEMBER…  
Member  
As  
On  
Select  
From  
Rows  
Columns  
Pages  
Sections  
Chapters  
NonEmptyReturns the set of tuples that are not empty from a specified set, based on the cross product of the specified set with a second set.NONEMPTY(<Set>1 [,set_expression2]) 
CrossJoinIt returns a set of tuples representing the cartesian product of the sets passed into it as parameters.
Enables you to create ‘nested’ or ‘crosstabbed’ axes in queries, same as using *
Crossjoin(<Set>1 ,Set_Expression2 [,…n] ) 
NonEmptyCrossJoinDeprecated – Do not use – Use Non Empty  
Where  
Solve_Order  
Format_String  
ClearCLEAR CALCULATIONS  
RollupChildren  
TM1Ignore_BadTuples  
TM1Format_String  
TM1RuleDerived  
TM1Subset_Ident  
TM1Update  
TM1Updateable  
TM1BangPrefix  


The MDX View related functions and related keywords above still need some expansion and some examples which will follow in the future.

As mentioned at the outset, please feedback to improve this post for everyone and let me know of any errors that need correction, examples that need updating etc. etc.